Google chief Larry Page ended speculation about his health Tuesday, disclosing that he has a "very rare" vocal condition that has weakened his voice but doesn't affect his day-to-day management.

In a post on the company's Google+ social networking service, the 40-year-old CEO wrote that he had been diagnosed with vocal-cord paralysis. After a bad cold 14 years ago, Mr. Page said that one of his vocal cords became paralyzed and his voice never fully recovered as doctors failed to find a cause.

Google Chief Executive Larry Page announced he has been diagnosed with vocal cord paralysis, which has left his voice softer than before and affected his breathing. George Stahl reports.

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Mr. Page said his condition took a turn for the worse last year when another cold brought problems to his second vocal cord. Since then, however, his condition has improved, he said.

Tuesday, Mr. Page said "I'm fully able to do all I need to at home and at work, though my voice is softer than before." He joked that Google co-founder Sergey Brin "says I'm probably a better CEO because I choose my words more carefully."

The revelation caps what had been a nearly 12-month mystery over Mr. Page's health. Mr. Page missed Google's annual shareholder meeting in June and other events after the Mountain View, Calif., company said he "lost his voice," though he continued to run the company. The lack of details surrounding the matter prompted speculation on Wall Street and elsewhere about whether Mr. Page may have had a serious medical condition.

Mr. Page subsequently told Google employees by email that there was "nothing seriously wrong with me," people familiar with the matter have said. Mr. Page's voice has continued to sound hoarse and raspy during earnings conference calls with investors.

Mr. Page's comments come one day before the start of Google's annual conference in San Francisco for software developers who create applications for Google's Android and Chrome computer-operating systems.

Google declined to make Mr. Page available for an interview and the company had no further comment.

Corporate governance experts said Mr. Page's disclosure was a responsible gesture to investors. Jeffrey Sonnenfeld, a senior associate dean at Yale School of Management, said Mr. Page's post stands "in sharp contrast with [former Apple Inc.AAPL-0.87% CEO] Steve Jobs's denials and efforts to disguise the truth for a fair bit of time."

Mr. Jobs died in 2011 at the age of 56 after suffering from pancreatic cancer. Apple's few disclosures about his health were criticized at times.

People in such high-profile jobs at public companies have a "responsibility to the public" to disclose their condition because they are so "central to the strategic value of the business," Mr. Sonnenfeld said.

Mr. Page's condition of vocal cord paralysis is caused when one or both of the vocal cords don't open and close correctly, resulting in difficulty speaking or breathing.

Michael Benninger, chairman of Cleveland Clinic's Head & Neck Institute, said based on Mr. Page's post, it appeared he had bilateral paralysis of his vocal cords, or folds. One fold appears to be improving while the other hasn't, he said.

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Bilateral paralysis is less common than unilateral paralysis of the vocal folds, Dr. Benninger said, and can be more difficult to treat as the goal is to get the folds further apart to improve the airway but not too far apart to worsen the voice. The paralysis is treatable, and there are surgical options available.

But "the challenge with bilateral is it's really more of an art, getting them to just the right distance where people can breathe better but still have a strong voice," said Dr. Benninger. It doesn't appear Mr. Page had surgery based on his Google+ post, Dr. Benninger added.

Dr. Benninger said the condition would "almost never" results in total voice loss.

In his post, Mr. Page offered more details on how his vocal cord paralysis has rippled out to other aspects of his health, including that his ability to exercise at "peak aerobic capacity is somewhat reduced" because of the vocal cord's effect on his breathing.

Mr. Page also wrote that it's unclear if his vocal cord issues are related to separate problems with his thyroid gland, though he added that the diagnosis in 2003 of Hashimoto's thyroiditis was "a fairly common benign inflammatory condition of the thyroid which causes me no problems."

Mr. Page added that he was funding a research program at the Voice Health Institute that will be led by Steven Zeitels of Harvard Medical School.

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